Her remains found last September in a remote area of Orange County have now been identified through dental records.
"She's no longer in pain thank goodness, but we need to find out who did it," said sister, Kim Gogos.
Family members believe she was murdered, but authorities cannot yet prove that.
"If she did pass away at the hands of someone else we have not located a crime scene, so at this time it still remains a mystery," said Sgt. Rick Martinez, Anaheim Police Department.
Dressed in a pink bathing suit, Cindy was last seen with her husband Donald Mathieu, August 14, 2004. They had left their son Sam at a family party in Buena Park.
"They were arguing pretty much the whole party. And when they left usually they would take Sam and he insisted on leaving Sam," said Cindy's nephew, Christopher Gogos.
According to Donald, he and Cindy returned to their Anaheim apartment and they slept in different rooms.
The next day, he says he couldn't find her. She left behind her clothes and her purse.
Family members say they haven't seen Donald since March 2005.
"He's next of kin if you care about her, come claim her. Come claim her if you've got nothing to hide," said Christopher Gogos.
Records show Anaheim Police arrested Donald in 2000 on suspicion of spousal battery. He was never convicted.
Family members knew the couple had a sometimes violent relationship.
"One time, he physically did choke her to where eyes were bloodshot," said daughter, Sarah Originales.
Hospital records obtained by Eyewitness News show Barbara Mathieu, Donald's wife before Cindy suffered injuries in Texas in 1992. She alleged Donald choked her.
Barbara sought a restraining order alleging he threatened to kill her. For some reason Barbara dropped her case against Donald.
She died in 1999 of natural causes.
Anaheim police say they haven't seen Donald in years and so far he is not a suspect in Cindy's death.